Shield with no MP consumption
1. Activate a shield (one using the Jupiter DSS card).
2. Enter a save location, and save your game, not turning off your shield.
3. Exit the save location, and your shield should still be going, with no consumption of your MP!

Unlock Extra Captains
You can unlock extra captains for offline modes by playing through Road to the Striker Cup:

Unlock stadiums
To unlock more stadiums for Domination Mode, you must play through Road to the Strikers Cup. Note: The Brick Wall Award is earned for conceding the least goals in the group stage. The Golden Foot Award is earned for scoring the most goals in the group stage.

Crystal Canyon - Win the Crystal Cup
Galactic Stadium - Earn both the Brick Wall Award and the Golden Foot Award in the Striker Cup
Stormship Stadium - Win the Striker Cup
The Dump - Earn both the Brick Wall Award and the Golden Foot Award in the Crystal Cup
The Lava Pit - Win the Fire Cup
The Wastelands - Earn both the Brick Wall Award and the Golden Foot Award in the Fire Cup